1986 (approx) Four Winns
Mercruiser MCM 140 #A676736 (from engine placard), 4 cylinder
3.0L (assumed)
PROBLEM
After cruising for a short time, the engine develops a “hardmiss” which is persistent once the engine is hot. The tach confirms RPMfluctuation. Must throttle back and can only idle after the miss hasdeveloped. Once the engine is turned off and has cooled, then it’spossible to cruise again for a short time before the engine warms up and the“miss” returns.
Ignition problem? Fuel problem?
The following were changed May, 2017:
34235 breaker
33662 condenser
18-5418 rotor
18-5385 cap
RV9YC plugs
Ignition?
Replace the ignition coil and spark plug wires?
Fuel?
Replace fuel filter in fuel pump? Replace any otherfilters or screens in the fuel line and carburetor? Gaskets?
I don't have a lot of high tech testingequipment. Can you help me out with an educated guess on this problem?
Mercruiser MCM 140 #A676736 (from engine placard), 4 cylinder
3.0L (assumed)
PROBLEM
After cruising for a short time, the engine develops a “hardmiss” which is persistent once the engine is hot. The tach confirms RPMfluctuation. Must throttle back and can only idle after the miss hasdeveloped. Once the engine is turned off and has cooled, then it’spossible to cruise again for a short time before the engine warms up and the“miss” returns.
Ignition problem? Fuel problem?
The following were changed May, 2017:
34235 breaker
33662 condenser
18-5418 rotor
18-5385 cap
RV9YC plugs
Ignition?
Replace the ignition coil and spark plug wires?
Fuel?
Replace fuel filter in fuel pump? Replace any otherfilters or screens in the fuel line and carburetor? Gaskets?
I don't have a lot of high tech testingequipment. Can you help me out with an educated guess on this problem?